Storage Classes

StorageClasses define different classes of storage in a cluster. They specify which provisioner to use, what parameters to pass, and how volumes should behave. StorageClasses enable dynamic provisioning of PersistentVolumes.

Key Concepts

StorageClass

A cluster-scoped template that defines how storage should be provisioned.

Provisioner

The volume plugin that creates PVs (e.g., CSI drivers, cloud providers).

Binding Mode

When to provision storage: immediately or when a pod needs it.

Default Class

The StorageClass used when PVCs don’t specify one.

StorageClasses are cluster-scoped resources. They are available to all namespaces and define how storage is provisioned across the entire cluster.

Required Permissions

Action	Permission
View StorageClasses	`iam:project:infrastructure:kubernetes:read`
Create StorageClass	`iam:project:infrastructure:kubernetes:write`
Edit StorageClass	`iam:project:infrastructure:kubernetes:write`
Delete StorageClass	`iam:project:infrastructure:kubernetes:delete`

Key Fields

Field	Description
provisioner	The volume plugin that creates PVs (required)
reclaimPolicy	What happens to PV when PVC is deleted (Delete or Retain)
volumeBindingMode	When to bind PV to PVC (Immediate or WaitForFirstConsumer)
allowVolumeExpansion	Whether PVCs can be resized after creation
parameters	Provisioner-specific configuration options
mountOptions	Options passed to the mount command

Volume Binding Modes

Mode	Description
Immediate	PV is provisioned as soon as PVC is created (default)
WaitForFirstConsumer	PV is provisioned when a pod using the PVC is scheduled

Use WaitForFirstConsumer for topology-aware provisioning. This ensures volumes are created in the same availability zone as the pod, preventing scheduling issues.

How to View StorageClasses

Select Cluster

Choose a cluster from the cluster dropdown.

View List

The list shows all StorageClasses in the cluster (cluster-scoped, no namespace filter).

Filter and Search

Use the search box to find StorageClasses by name or provisioner. Filter by binding mode (Immediate, WaitForFirstConsumer).

How to View StorageClass Details

Find the StorageClass

Locate the StorageClass in the list.

Click StorageClass Name

Click on the StorageClass name to open the detail drawer.

Review Details

View StorageClass information including:

Overview: Name, provisioner, reclaim policy, binding mode, age
Features: Volume expansion, default status
Parameters: Provisioner-specific configuration
Mount Options: Mount command options
Allowed Topologies: Zone/region constraints
Labels & Annotations: Metadata

How to Create a StorageClass

Click Create StorageClass

Click the Create StorageClass button in the page header.

Write YAML

Enter the StorageClass manifest in YAML format. Key fields:

provisioner - Volume plugin identifier (required)
reclaimPolicy - Delete or Retain
volumeBindingMode - Immediate or WaitForFirstConsumer
allowVolumeExpansion - true/false
parameters - Provisioner-specific options

Create

Click Create to apply the manifest.

How to Edit a StorageClass

Open Actions Menu

Click the actions menu (three dots) on the StorageClass row.

Click Edit YAML

Select Edit YAML to open the YAML editor.

Modify Spec

Edit the StorageClass specification. Note that most fields are immutable after creation.

Save

Click Update to apply changes.

Most StorageClass fields (provisioner, parameters, reclaimPolicy, volumeBindingMode) are immutable after creation. To change these, delete and recreate the StorageClass.

How to Delete a StorageClass

Open Actions Menu

Click the actions menu on the StorageClass row.

Click Delete

Select Delete from the menu.

Confirm

Confirm the deletion. Existing PVCs using this class will not be affected.

Deleting a StorageClass prevents new PVCs from using it for dynamic provisioning. Existing PVCs and PVs are not affected.

Default StorageClass

One StorageClass can be marked as the cluster default. PVCs that don’t specify a storageClassName will use the default class. Setting the default:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: kubernetes.io/aws-ebs

Annotation	Description
`storageclass.kubernetes.io/is-default-class`	Set to `"true"` for default (recommended)
`storageclass.beta.kubernetes.io/is-default-class`	Legacy annotation, also supported

Only one StorageClass should be marked as default. If multiple are marked, behavior is undefined and may vary by Kubernetes version.

Example StorageClasses

AWS EBS (CSI)

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: ebs-gp3
provisioner: ebs.csi.aws.com
parameters:
  type: gp3
  fsType: ext4
  encrypted: "true"
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true

Google Cloud Persistent Disk

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: pd-ssd
provisioner: pd.csi.storage.gke.io
parameters:
  type: pd-ssd
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true

Azure Disk

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: azure-premium
provisioner: disk.csi.azure.com
parameters:
  skuName: Premium_LRS
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true

Local Storage

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: local-storage
provisioner: kubernetes.io/no-provisioner
reclaimPolicy: Retain
volumeBindingMode: WaitForFirstConsumer

NFS (External Provisioner)

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: nfs-client
provisioner: nfs-subdir-external-provisioner
parameters:
  archiveOnDelete: "false"
reclaimPolicy: Delete
volumeBindingMode: Immediate

Common Provisioners

Provisioner	Description
`ebs.csi.aws.com`	AWS EBS CSI driver
`pd.csi.storage.gke.io`	Google Cloud Persistent Disk CSI
`disk.csi.azure.com`	Azure Disk CSI driver
`file.csi.azure.com`	Azure File CSI driver
`csi.vsphere.vmware.com`	VMware vSphere CSI
`rook-ceph.rbd.csi.ceph.com`	Rook Ceph block storage
`kubernetes.io/no-provisioner`	No dynamic provisioning (local storage)

Troubleshooting

PVC stuck in Pending with no provisioner

Verify the StorageClass exists
Check provisioner pods are running
Ensure CSI driver is properly installed
Check for errors in provisioner logs

Volume provisioned in wrong zone

Use volumeBindingMode: WaitForFirstConsumer
Configure allowedTopologies if needed
Verify pod has appropriate node selectors

Volume expansion not working

Verify allowVolumeExpansion: true in StorageClass
Check if the provisioner supports expansion
Pod restart may be required for filesystem expansion
Check PVC conditions for resize status

Cannot create PVC with StorageClass

Verify StorageClass exists: kubectl get sc
Check PVC storageClassName matches exactly
Verify provisioner has necessary permissions
Check provisioner logs for errors

Default StorageClass not being used

Verify annotation is exactly storageclass.kubernetes.io/is-default-class: "true"
Ensure only one StorageClass is marked as default
Check PVC doesn’t explicitly set storageClassName: ""

Parameters not taking effect

Parameters are passed directly to the provisioner
Check provisioner documentation for valid parameters
Verify parameter values are strings (quoted in YAML)
Invalid parameters may be silently ignored

FAQ

What is dynamic provisioning?

Dynamic provisioning automatically creates PVs when PVCs are created. The StorageClass specifies the provisioner and parameters used to create the storage. No manual PV creation is needed.

When should I use WaitForFirstConsumer?

Use WaitForFirstConsumer when:

Using multi-zone clusters
Storage must be in the same zone as the pod
Using local persistent volumes
Topology-aware provisioning is needed

It delays provisioning until a pod is scheduled, ensuring the volume is created in the correct location.

Can I change a StorageClass after creation?

Most fields are immutable (provisioner, parameters, reclaimPolicy, volumeBindingMode). You can only modify labels, annotations, and allowVolumeExpansion. To change other fields, delete and recreate the StorageClass.

What happens to existing PVCs if I delete a StorageClass?

Existing PVCs and PVs are not affected. They retain their original settings. Only new PVCs cannot use the deleted StorageClass.

Should I have multiple StorageClasses?

Yes, typically. Create different StorageClasses for:

Different performance tiers (SSD vs HDD)
Different reclaim policies (Delete vs Retain)
Different use cases (databases vs logs)
Different availability zones or regions

What is the difference between Delete and Retain reclaim policies?

Delete: When PVC is deleted, PV and underlying storage are automatically deleted. Good for ephemeral data.Retain: PV is kept when PVC is deleted, allowing manual data recovery. The PV enters “Released” state.

How do mount options work?

Mount options are passed to the mount command when attaching volumes. Common options include ro (read-only), noatime, nodiratime. Not all provisioners support mount options.

What are allowed topologies?

Allowed topologies restrict where volumes can be provisioned based on node labels (typically zones/regions). This ensures volumes are only created in specific locations, useful for compliance or performance requirements.

Getting Started

Infrastructure

Platform Services

CI/CD & Deployments

Pipeline & Helm

Performance Testing

Security

Mesh Networking

Access Management

Audit & Compliance

Settings

Key Concepts

StorageClass

Provisioner

Binding Mode

Default Class

Required Permissions

Key Fields

Volume Binding Modes

How to View StorageClasses

How to View StorageClass Details

How to Create a StorageClass

How to Edit a StorageClass

How to Delete a StorageClass

Default StorageClass

Example StorageClasses

AWS EBS (CSI)

Google Cloud Persistent Disk

Azure Disk

Local Storage

NFS (External Provisioner)

Common Provisioners

Troubleshooting

FAQ

​Key Concepts

StorageClass

Provisioner

Binding Mode

Default Class

​Required Permissions

​Key Fields

​Volume Binding Modes

​How to View StorageClasses

​How to View StorageClass Details

​How to Create a StorageClass

​How to Edit a StorageClass

​How to Delete a StorageClass

​Default StorageClass

​Example StorageClasses

​AWS EBS (CSI)

​Google Cloud Persistent Disk

​Azure Disk

​Local Storage

​NFS (External Provisioner)

​Common Provisioners

​Troubleshooting

​FAQ

Key Concepts

Required Permissions

Key Fields

Volume Binding Modes

How to View StorageClasses

How to View StorageClass Details

How to Create a StorageClass

How to Edit a StorageClass

How to Delete a StorageClass

Default StorageClass

Example StorageClasses

AWS EBS (CSI)

Google Cloud Persistent Disk

Azure Disk

Local Storage

NFS (External Provisioner)

Common Provisioners

Troubleshooting

FAQ